Field of the Invention
The present invention relates to an adsorbing deacidifier or deacidifying agent for oily substances, and has for its object to provide a deacidifier in a powder form, which is capable of effecting deacidification of oily substances through simple procedures by adding the deacidifier to an oily substance, with subsequent filtering after stirring for mixing.
The oily substances referred to in the present invention indicate animal and vegetable fats, mineral oils, solvents, etc., and are used to correspond to the water soluble substances.
In cases where fried foods such as fried noodles, potato chips, dough-nuts, and fried beans, etc. are to be manufactured, since frying oil is repeatedly used in a frying pan, it tends to change in quality through the thermal oxidation, hydrolysis or the like thus resulting in a rise of acid value (referred to as AV hereinbelow) together with deteriorations such as coloring, increase of viscosity, etc. Recently, qualities of frying oils have been brought into question from the viewpoint of nutrition, with the qualities thereof being generally evaluated by AV. With respect to the fried noodles, AV of oils contained therein is prescribed to be less than 3.0 by the Food Sanitation Act in Japan. The main substances for the acid component which increases AV as described above are considered to be carboxyl group to be produced by thermal oxidation and free fatty acid to be produced by hydrolysis, and such acid components also have the so-called autocatalysis function for again assisting in the hydrolysis of the oils. Accordingly, if it is possible to remove the very small amount of acid component initially produced in the frying oil at all times, hydrolysis of the frying oil will be suppressed to a remarkable extent, with the increase of AV being advantageously prevented. At present, for the purpose of removing fine particles produced from materials to be fried, filtering of the frying oil after completion of frying work through employment of diatomaceous earth, etc. as a filter aid, has been widely effected, but by using the adsorbing deacidifier according to the present invention instead of the filter aid, the acid component is also removed together with the fine pariticles, and thus, the frying oil may be maintained at a low AV.
It should be noted here that the adsorbing deacidifier according to the present invention is not limited, in its application, merely to frying oils alone, but may effectively utilized for the purpose of regeneration of cutting oils, cleaning solvents, etc.
For deacidifiers for oily substances, there have conventionally been known such substances as magnesium oxide (U.S. Pat. No. 3,231,390), aluminum hydroxide gel (Japanese Patent Publication Tokugansho No. 47-50245), etc., but these known materials have such disadvantages that in the former, magnesium soap to be produced dissolves into oil, while in the latter, adsorbing capacity for acid component is undesirably small, thus not being favorable from the economic point of view.
Zeolite means a "boiling stone" in Greek, and mineralogically belongs to the group of zeolite. Today, not only natural zeolite, but many synthetic products thereof are being produced. Originally, zeolite is an aluminosilicate of alkali and alkaline earth metal, and contains water as a main component in the crystal lattice. The water of crystallization referred to above may be considerably easily eliminated partly or on the whole, through heating or pressure reduction, but substantially, destruction of crystal structure does not take place. It may be said that the structural feature of zeolite resides in the formation of hollow structure by a variety of combination systems of the structural unit. Such hollow structure has a property for easy recondensation, and even in this case, there are no structural change after adsorption or swell characteristics, without destruction by water, either. Meanwhile, as compared with other moisture absorbing agents such as silica gel, active alumina, etc., zeolite has such characteristics that it has a large moisture absorbing capacity even at a low humidity, with a high moisture absorbing strength. It is another feature of zeolite that it has a large moisture absorbing capacity, with a high moisture absorbing strength even at comparatively high temperatures. Additionally, although zeolite has a property to selectively adsorb polar substances through action of cation in the hollow structure, it has no properties to adsorb acid components in oily substances.